Method of renewing strainer-plates for paper-machines



(No Model.)

' F. WILLIAMS METHOD OF RENEWING STRAINER PLATES FOR P APER MACHINES.No. 881,737. Patented Apr. 24, 1888.

I U l H a J I LUITNESSES [BR/ENTER. M%MMI 55W 9W- UNiTsD STATES PATENT@rrrcet FRANK lVILLIAMS, OF HOLYOKE, MASSACHUSETTS.

METHOD OF RENEWING STliAlNERPLATES FOR PAPER-MACHINES.

SPECIFICATION forming part of Letters Patent No. 381,737, dated April24, 1888.

Application filcd May 20, 1887. Serial No. 239,854. (No model.)

To aZZ whom it may concern:

Be it known that I, FRANK \VILLLLMS, of Holyoke, in the county ofHampden and Commonwealth of Massachusetts, have invented a new anduseful Method of Renewing Strainer or Screen Plates of Paper-lllachines,of which the following is aspccification, refer ence being bad to theaccompanying drawings, forming part thereof.

My invention relates to renewing or repairing the plates through whichthe pulp from which paper is made is screened or strained as it enters apapenmachine for the purpose of removing therefrom knots and other solidparticles, which, if not eliminated, would injure the quality of thepaper. The work performed by these plates is one of great impor tance,and the greatest care isjexercised in their manufacture. The face orupper surface when in use is made perfectly smooth and level, and withinthis face is the series of fine slots through which the pulp isstrained, the rear or lower side being formed into ribs extendingbetween the slots to give the necessary stiffness to theplate. The slotsare cut with a circular saw, and the substance composing the plate mustbe soft enough to enable the saw to act thereon, while it must also beof a nature to withstand as much as possible the corrosive action of theacids contained in the pulp. These two requirements have resulted in theuse of brass and compositions of metal in which it is the principalingredient as the material from which the plates are made. It has beenfound to be impossible to construct a plate, however, which will for anygreat length of time withstand corrosion and the wear caused by thesolid particles removed from the pulp, and the result is that the slotsin the plate become widened to such an extent as to render the platesinoperative to properly strain the pulp, and they then must be renewedor be replaced by new ones. I am aware of two methods by which it hasheretofore been proposed to renew such worn plates. In one of saidmethods the strainer-plate is held with its face uppermost upon a tableor bed by means of clamps which engage the plate at intervals about itssides, and is operated upon by a tool the end of which is adapted tobear upon the plate upon both sides of a slot therein, and having ablade projecting beyond said end. The blade is inserted within the slot,and the metal forming the sides of the slot is forced against said bladeby striking the upper end of the tool with a hammer, the width of theblade regulating the width of the slot. In the second method referredto, the plate is also placed face uppermost upon a table or bed, noclamp being employed to hold it, 110wever, and thin strips of metal areinserted lengthwise within the slots, after which a roller having agrooved periphery to bear upon the plate upon each side of a slot iscaused to traverse from one end of the slot to the other under pressure,whereby the walls of the slot are forced against the interposed strip inthe same manner as by the first method mentioned they are forced againstthe blade projecting from the tool. These methods are both open toserious objections, and both fail to effectively accomplish the resultaimed at. In the first place they both depend upon a pressure exertedvertically against the face of the plate at the sides of the slotstherein and between the Vertical planes of the ribs at the rear side ofthe plate, at which point there is nothing to resist such pressureexcept the this web of the plate between the ribs, which is elevatedabove the table or bed a distance equal to the depth of the ribs. Theresult is that the pressure of the tool or roller depresses thesethinner portions of the plate beneath the level of the thicker portionswhere the ribs occur, and the face is caused to become full of ridgesand de pressions, which mustbe removed by planing off the face beforethe plate can be used. As the thickness of the plate between the ribs isonly one-sixteenth of an inch, such removal of the metal by planingweakens the plate materially at the very point where strength isrequired to withstand the wear to which it is subjected. Even where thepressure exerted is'not sufficient to thus wholly depress portions ofthe plate the indentations caused by the tool in the method firstreferred to, as the same is struck by a hammer and moved back and forthover the face of the plate, must all be removed by planing before theplate can properly perform its function. Again, the pressure beingexerted by the tool or roller upon the said thin portion of the plate,with nothing directly beneath it to support it, the side walls of theslot are not squarely brought to check and remove the solid particlescontained in the pulp at any point beneath said surface, the divergingwalls of the slot will render it too wide to perform such function,

and as a consequence, whenever the sides of the slot at the surfacebecome slightly worn away, the said particles are free to pass bodilythrough the plate, whereas if the walls of the slot were parallel fromtop to bottom they would effectively perform their straining-functionuntil worn away through the whole thickness of the plate. Still. anotherobjection to these methods is that, the strainer-plate being clamped tothe bed-plate at intervals only in the one case and not at all in theother, said strainer is free to expand under the pressure exerted uponit as much in one direction as another, and consequently it is liable tobe distorted and forced out of its original shape and dimensions, whenit is rendered practically useless.

It is the object of my invention to devise a method by the practice ofwhich strainerplates in which the slots have become worn and widened canbe restored to the same condition in which they were when new withoutdiminishing the thickness of the plate or weakening it in any respect,and without marring its face or changing its shape or proportions.

To this end my invention consists in the novel method comprising thetreatment of stra1ner-plates upon their rear side instead of their face,hereinafter fully described, and particularly pointed out in the claims.

Referring to the drawings, in which like 1 letters designate like partsin the several figures, Figure 1 is a perspective view of thestrainer-plate secured to the bed-plate in 'position to be operatedupon, and showing the operating-tool in engagement with one of the ribsthereof. Fig. 2 is a longitudinal section thereof, taken upon the line9200 in Fig. 1. Figs. 3 and 4 are side and front views, respectively, ofthe operating-tool. Fig. 5 is a view of one half of a strainer-plate,showing the face of the plate when new or in perfect condition. Fig. 6is a view of the other half of said plate, showing its appearance whenthe slots have become worn and widened. Fig. 7is a front view of anotherform of operating-tool. 1

The letter D designates the strainer-plate, having the slots d in itsface. The side walls of the slots at are parallel for a distance ofonesixteenth of an inch from the surface of the plate, at which pointthey diverge, at first abruptly to form a slight shoulder, and thengradually to the bottom of the plate, thus for1n= ing the ribs 11between the'slots. The metal at each side of each slot is thus leftonesixteenth of an inch in thickness, while the thickness of the platethrough the ribs d is from one-fourth to five-sixteenths of an inch. Inmanufacturing these plates-the metal between the ribs is removed fromthe rear side by milling, after which the face is made perfectly smoothand true, and the slots d are then cut with a circular saw. When new,the face of the plate presents the appearance shown in Fig. 5; but thecorrosive action of the acids in the pulp and the wear caused'bystraining the pulp through the slots soon widen the latter and causetheir edges to become rough and uneven, .as shown in Fig. 6. When inthis condition, the plate will not properly strain the pulp, and must berenewed by closing up the side walls of the slots to restore the latterto their former width.

In practicing my novel method of making such renewal I place the plateface downward upon a metallic bed-plate, B, as shown in Figs. 1 and 2,the upper surface of said bed-plate being planed perfectly true. Thestrainerplate is secured to the bed plate by clamps which bearcontinuously upon the sides of the former throughout their length. Tosecure this result I have devised the clamp shown in the drawings, whichconsists of bars A A, adjustably secured to the sides of the bed-plateby bolts 1) passing through vertical slots 0 in said bars into thebed-plate, washers 12 being interposed between the heads of the boltsand the bars. g

The clamp-plates A A each have an inwardly-projecting lip which extendsover the bedplate and the strainer-plate placed thereon, as shown. Byloosening bolts 6 the clamp-plates can be raised and loweredindependently of the bed-plate, and when their projecting lips areforced down upon the strainer-plate and said bolts are tightened thesaid plate is securely and continuously held along its sides, so thatexpansion thereof in either direction is prevented. The bed-plate willpreferably be of the exact width of the strainer-plate, so that thesides of thelatter will abut against the vertical inner walls of theclamp-plates A A to prevent expansion of the strainer-plate in thedirection of the length of the slots therein; but by the use of gibs,consisting of thin metal strips inserted at the sides of thestrainer-plate, a bed-plate wide enough to accommodate strainer-platesof different widths can be used. The strainer-plate being thus securedto the bed-plate, a tool, L, having in its lower end a slot conformingto the shape of the ribs d in cross-section and of sufficient depth toreceive the greater part of a rib, is applied to one of the ribs, asshown in Figs. 1 and 2. The operator then administers a series of blowsupon the end of the tool with a hammer or mallet, moving the tool alongthe rib after each blow. That portion of the rib received within thetool being prevented from lateral expansion, and the rib being preventedfrom longitudinal expansion by the clamps at the sides of thestrainer-plate, it follows that the pressure exerted by the blows on thetool will cause the metal to expand at the face of the plate betweentheslots d. A gain, the pressnre being exerted perpendicularly to the planesurface of the bed-plate B, the expansion must he at a right angle tothe vertical walls of the slots d, and therefore said walls are causedtoapproach each other squarely and parallel with each other, thusdiminishing the width of the slot. The face of the strainer-plate,beingheld in contact with the surface of the bed-plate, is

rendered perfectly smooth and true, and consequently does not requireplaning or other treatment to put it in condition for use.

Byexercising the proper amount of care the operator can close the slotsd to their proper width with the tool alone; but I prefer to close themup entirely,and then, removing the plate, resaw them with a circularsaw,as is done when the plates are manufactured, and I thus practicallytransform the wornout plate into a new one. Instead of the tool L, aroller, M, having a peripheral groove corresponding in outline to theslot in the tool, can be employed either as part oi a hand implement ormounted in the head of a press or similar machine having means forapplying pressure to said roller and for reciprocating the bed-plale Bbeneath it, whereby the roller can be caused to move back and forth uponthe ribs of the strainer-plate. Such a roller is shown in Fig. 7. Itsopera tion upon the strainer-plate,whether used as a tool or as part ofa machine, is identical with that of the tool just described.

When the slots have been completely closed and resawed, as described,their side walls are vertical and parallel, and the plate is renderedcapable of withstanding wear fully as long as when new, and as thethickness of the plate is not diminished, the plates can be renewedseveral times before being finally abandoned.

It will be observed that by the practice of my method, as distinguishedfrom the methods of operating upon the face side of the platehereinbefore referred to, I secure the all important advantages ofretaining the full thicle ness of the plate, closing the slots withtheir sides parallel to each other throughout their length, andpreserving the smooth even surface of the plate. It will also beobserved that the method herein set forth can be practiced irrespectiveof the particular apparatus shown and described, and I therefore do notwish to limit myself to such apparatus.

Having thus fully described my invention, what I claim, and desire tosecure by Letters Patent, isi 1. The method of renewing strainer orscreen plates of paper-machines herein set forth,which consists insecuring the plate face downward upon a suitable bed by means of clampsbearing continuously ,upon two sides of the plate, and applyingsufficient pressure to the ribs upon the rear side of the plate toexpand the metal at the face of the plate and decrease the width of theslots therein, substantially as de scribed.

2. The method of renewing strainer or screen plates ofpaper-machines,whieh consists of the following steps, viz: first,securing the plate face downward upon a bed-plate by means of clampsbearing continuously upon two sides of the formerplate; second,applyingsufficient pressure to the ribs at the rear side of the plate to expandthe metal at the face of the plate and completely close the slotstherein, and, third, making new slots in the plate, substantially as setforth.

FRANK wiLLrAMs.

Witnesses:

W. H. CHAPMAN, J. E. CHAPMAN.

